The present invention generally pertains to data recording systems and is particularly directed to a system for recording data on tape in a disk recording format.
The five and one-quarter inch Winchester recording disk which provides substantial storage capacity and rapid data access is becoming increasingly popular as a principal memory for personal and small business computers, which until recently, used exclusively flexible or floppy disk memories. A five and one-quarter inch Winchester disk may have a memory storage capacity of, for example, fifty-five megabytes. On the other hand, a typical floppy disk may have a storage capacity of only one-quarter megabyte.
Many computer systems have backup memory devices to assure against malfunctions or physical damage that could destroy the principal data bank. In the past, in personal and small business computer systems, the backup storage unit has typically consisted of a second floppy disk drive. However, the increasing use of five and one-quarter inch Winchester disk drives in personal and small business computers has created a need for greater backup storage. Floppy disk drives are unsuitable for use as backup storage for a five and one-quarter inch Winchester disk drive because the hard disk stores many times more information than a single floppy disk. For example, forty one-quartermegabyte floppy disks would be needed to back up one ten megabyte Winchester disk drive, making backup storage a time-consuming inconvenience for the operator.
Magnetic tape is a more practical form of backup storage for the five and one-quarter inch Winchester recording disk.
A typical prior art system for recording data on a floppy recording disk 9 is shown in FIG. 1. This prior art system includes a disk recorder controller 10, a host interface circuit 11, a control logic circuit 12, a write logic circuit 13, a read logic circuit 14, a spindle 15, a transducer head assembly 16, a stepper motor 17, a drive motor 18, a motor drive circuit 19, a "track 00" switch 20, a write protect switch 22, an index pulse LED (light emitting diode) 23 and an index pulse detector 24. The disk 9 is contained in a diskette 21, and is engaged on the spindle 15 for rotation within the diskette 21.
A CPU (central processing unit) 25 is connected to the disk recorder controller 10 by a bus 26. Data, addresses and control signals are communicated between the CPU 25 and the disk recorder controller 10 over the bus 26.
Signals are communicated between the disk recorder controller 10 and the control logic circuit 12 via a bus 27, the host interface circuit 11 and lines 29, 30, 31, 32 and 33.
Step command signals and a direction select signal from the disk recorder 10 are provided on lines 29 and 30 respectively to the control logic circuit 12 for controlling which track of the recording disk 9 is accessed by the transducer head. The recording disk 9 has concentric tracks. The control logic circuit 12 provides stepper A, B, C and D control signals on lines 35, 36, 37 and 38 to the stepper motor 17. The control logic circuit 12 provides a "track 00" signal on line 31 to the disk recorder controller 10 when the transducer head is accessed to the outermost track on the disk. The control logic circuit derives the "track 00" signal from line 40 which is connected to the "track 00" switch 20, together with a common line 41.
A "motor on" signal from the disk recorder controller 10 is provided on line 33 to the control logic circuit 12 for controlling the drive motor 18. The drive motor 18 is coupled to the spindle 15 for rotating the turntable so that the transducer head can access various locations on each concentric track of the recording disk. The control logic circuit 12 provides motor drive signals on line 42 to the motor driver circuit 19, which in turn provides motor control signals on line 43 to the drive motor 18. A speed signal is provided on line 45 to the motor driver circuit 19 from a tachometer attached to the drive motor 18 for completing a servo loop for controlling the speed of the drive motor 18.
The control logic circuit 12 provides a "head load solenoid" signal on line 46 to the transducer head assembly 16 for placing said transducer head in contact with the recording disk 9, thereby allowing recording on the recording disk 9.
The control logic circuit 12 provides an index pulse on line 32 to the disk recorder controller 10 for every rotation of the disk 9. The control logic circuit 12 generates the index pulse on line 32 in response to receiving an index pulse detection signal on line 47 from the index pulse detector 24. The index pulse detector 24 detects light from the index pulse LED 23 that is transmitted through a hole 48 in the disk 9 at a fixed point during each rotation of the disk 9. The index pulse LED 23 is energized by a signal on line 49 from the control logic circuit 12.
The format for recording on the recording disk 9 is keyed to the reception of index pulses by the disk recorder controller 10. The controller 10 responds to the index pulse when in a formatting mode by providing a recording signal to the write logic circuit 13 on line 51 for formatting a recorded track on the disk 9. The recording signal for each track includes a first fill field, followed by a predetermined number of sectors including identifying addresses and data, followed by a second fill field until the index pulse is again received upon completion of one revolution of the disk 9. Recording is enabled only when a "write gate" signal is provided by the disk recorder controller 10 to the write logic circuit on line 52. The write logic circuit 13 provides the signal to be recorded to the transducer head via line 53.
A write protect switch 22 is provided for connection to a recording disk when it is desired to prevent recording on the disk 9. The write protect switch 22 is connected to the write logic circuit 13 by a signal line 54 and a common line 55. The write logic circuit 13 provides a "write protect" signal on line 57 to the disk recorder controller 10 to prevent the controller 10 from providing recording signals on write data line 51.
The signals on lines 51, 52 and 57 are communicated between the disk recorder controller 10 and the write logic circuit via bus 27 and the host interface circuit 11.
The read logic circuit 14 receives signals read by the transducer head on line 59 and conditions and provides the received read data signals on line 61 to the disk recorder controller 10 via the host interface circuit 11 and bus 27.